The present application relates to a semiconductor structure and a method of forming the same. More particularly, the present application relates to back-end-of-the-line (BEOL) resistors that have high precision as well as methods of forming such BEOL resistors.
A resistor, which is a passive two-terminal electrical component that implements electrical resistance as a circuit element, is one of the most common electrical components present in almost every electrical device. In electronic circuits, resistors can be used to limit current flow, to adjust signal levels, bias active elements, and terminate transition lines.
In semiconductor devices, it is well known to have a thin film resistor such as, for example, a resistor composed of TaN, embedded in the chip through either a damascene approach or a subtractive etch method. For example, and during back-end-of-the-line (BEOL) processing, a thin film resistor may be embedded in an interconnect dielectric material; such structures may be referred to as BEOL resistors. Prior art methods of forming thin film resistors embedded in an interconnect dielectric material are complicated and expensive. Moreover, topography issues arise when embedding a thin film resistor in an interconnect dielectric material which may degrade the final chip yield. Other issues with prior art methods of embedding a thin film resistor in an interconnect dielectric material include, but are not limited to, Joule heating and poor scaling capabilities.
Moreover, precision BEOL resistors used in analog circuits need to have small tolerances of variation and need to integrate in with the overall BEOL process flow in a way that minimizes cost, space and/or wiring congestion.